USB protocol technology is a serial bus standard by which a host is connected to a peripheral, which is widely used on a host (such as a personal computer, a personal digital assistant and a mobile computer, etc.). USB protocol technology supports hot-plug, instant plug-and-play and power supply via bus. Almost all peripherals such as mouse, keyboard, game handler, scanner, digital cameral, printer, hard disk, security device, disc driver and net card, can connect to and communicate with a host by operation of USB interface. So USB interface has become a default interface connecting most of the current host peripherals and a computer.
In some situation, a device should know type of operating system on a computer connecting to it. However, in the prior art the device cannot identify operating system on a host.